The present disclosure relates to a power feeding system that performs power supply (power feeding, electricity transmission, or power transmission) in a noncontact manner to an objective unit such as an electronic unit, and to an electronic unit applicable to such a power feeding system.
Recently, a power feeding system (a noncontact power feeding system or a wireless charging system), which supplies power in a noncontact manner to consumer electronics (CE) devices such as a mobile phone and a portable music player, is the subject of interest. Such a noncontact power feeding system makes it possible to start charge only by placing an electronic unit (a secondary unit) on a charge tray (a primary unit) instead of starting charge by inserting (connecting) a connector of a power supply unit, such as an AC adaptor, into a unit. In other words, such a system eliminates necessity of terminal connection between the electronic unit and the charge tray.
A method of performing such noncontact power supply is roughly classified into two techniques. A first technique is a widely known, electromagnetic induction method capable of efficient power feeding due to its extremely high coupling degree between an electricity transmission side (primary side) and an electricity reception side (secondary side). A second technique is a so-called magnetic resonance method that is characterized in that a small amount of magnetic flux may be satisfactorily shared by the electricity transmission side and the electricity reception side by actively using a resonant phenomenon.
In recent years, the trend of standardization has been developing, and standardization is actively advanced mainly by an industry group named Wireless Power Consortium (WPC). The standardization enables compatibility between products of different enterprises, and enables charge in many combinations of primary units and secondary units. For example, Japanese Unexamined Patent Application Publication Nos. 2001-102974, 2008-206233, 2002-34169, 2005-110399, and 2010-63245, and International Patent Application WO 00/27531 each disclose such a noncontact power feeding system.